1. Field of the Invention
This invention relates to an apparatus for transporting and aligning objects and more specifically to an apparatus that aligns two objects as they are transported through a process.
2. Description of Related Art
In the apparel industry, the sewing of fabrics often require that the edges of two pieces of fabric be joined in a seam wherein the ends of these pieces must be even or matched within a very close tolerance after they are sewn together. Although these pieces may be cut precisely equal in length, several factors affect the overall matching of the edges after these fabrics have been sewn. These factors include the friction of the fabric passing through the machine and folding devices, varying characteristics of the fabrics themselves and the asymmetrical feed or pull that the sewing machine exerts on the top and bottom fabric pieces.
If after being sewn, a mismatch is produced between two fabrics which is greater than the next operation can correct or which does not meet the standard of quality in a case of a finishing operation, the piece is considered defective and the stitching must be ripped out and the pieces resewn.
If the length of the sewing operation is sufficient, the operator may control the tolerance to some extent by the application of tension or drag on one of the pieces of fabric as it is being sewn. However, it is very difficult to maintain a high degree of consistency because of the varying characteristics of materials from piece to piece, the high operating speed of modern sewing machines and operator fatigue. The shorter the length of the sew, the less manual correction that can be made because of both mechanical and physical response limitations. The existence of this alignment problem has in many incidences resulted in the abandonment of attempts to automate sewing operations in the apparel industry.
One object of the present invention is to provide an apparatus that automatically tracks material as it is being processed, generating a signal indicative of alignment and controlling alignment of the material.